The present invention relates generally to a sensor for determining the presence of an occupant within an automotive vehicle and more specifically, to an occupant sensor incorporated within the seat belt that may be used to control the deployment of an airbag.
In the first iteration of airbags for automotive vehicles, the airbags deployed upon sensing a predetermined deceleration of the vehicle. The airbags deployed at a predefined rate without regard to other input.
More recently, airbags have been developed that deploy at a lesser rate than early airbags. These airbags, however, also do not take into consideration other factors. For example, both a passenger side and driver side airbag deploy simultaneously without regard to whether a passenger is present.
Various methods for determining the presence of an occupant have been proposed. These sensors include infrared sensors directed to the passenger area, weight sensors that are located under the seat, and seat belt use sensors that measure the radius of the webbing spooled upon the retractor. The radius of the webbing may be determined by a mechanical type sensor that measures the thickness of the web around the spool. The drawback to retractor systems is that because the designs are mechanical, the moving parts must be assembly,
It would be therefore be desirable to provide a sensing system for detecting the presence of a seat occupant, which addresses these concerns.
It is therefore one object of the invention to provide an occupant sensing system that accurately and reliably measures the presence of an occupant in a seating position. It is a further object of the invention to adjust the deployment of an airbag in response to the occupant sensor.
In one aspect of the invention, an occupant sensor includes a seatbelt and a plurality of wires extending a predetermined length of the seat belt that conforms to the shape of the seat belt. A controller is coupled to the plurality of wires and measures a change in the electrical characteristics of the wire and indicates the presence of an occupant in response to the electrical characteristic.
In a further aspect of the invention, the occupant sensor is coupled to an airbag controller. The airbag controller adjusts the airbag deployment strategy in response to the electrical characteristic.
In a further aspect of the invention, a method for determining the presence of an occupant within an automotive vehicle comprises the steps of:
passing an electrical signal through wires within a length of a seat belt, said wires have a shape;
measuring a seat belt electrical characteristic of said wires;
comparing the seat belt electrical characteristic to a known characteristic; and
indicating the presence of a occupant in response to the step of comparing.
One advantage of the invention is that not only may the presence of an occupant be detected, but the size of the occupant may also be detected.
Another advantage of the sensor is that it may be incorporated into the seat belt without significant expense and operates electrically without moving mechanical parts.